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https://issues.apache.org/jira/browse/HADOOP-2434?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12552141
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Raghu Angadi commented on HADOOP-2434:
--------------------------------------
Good catch. I noticed this when I was working on HADOOP-2012. I fixed it there
but didn't think it would affect so much.
Could you try the following fix? {noformat}
Index: src/java/org/apache/hadoop/dfs/FSDatasetInterface.java
===================================================================
--- src/java/org/apache/hadoop/dfs/FSDatasetInterface.java (revision
601589)
+++ src/java/org/apache/hadoop/dfs/FSDatasetInterface.java (working copy)
@@ -64,8 +64,8 @@
}
@Override
- public int read(byte[] b) throws IOException {
- return inStream.read(b);
+ public int read(byte[] b, int off, int len) throws IOException {
+ return inStream.read(b, off, len);
}
public long getLength() {
{noformat}
> MapFile.get on HDFS in TRUNK is WAY!!! slower than 0.15.x
> ---------------------------------------------------------
>
> Key: HADOOP-2434
> URL: https://issues.apache.org/jira/browse/HADOOP-2434
> Project: Hadoop
> Issue Type: Bug
> Components: io
> Reporter: stack
> Attachments: TestMapFile.java, TestMapFile.java
>
>
> Stall happens down in SequenceFile in the first call to getPos inside
> readRecordLength. I tried the johano patch from HADOOP-2172 that restores
> the positional cache but that didn't seem to be the issue here.
> Here is data to support my assertion.
> I wrote a little program to make a MapFile of 1M records. I then did 1M
> random reads from same file. Below are timings from a 0.15.0 and TRUNK as of
> this afternoon run.
> 0.15.x branch:
> {code}
> [EMAIL PROTECTED] branch-0.15]$ ./bin/hadoop org.apache.hadoop.io.TestMapFile
> .07/12/15 01:29:02 WARN util.NativeCodeLoader: Unable to load native-hadoop
> library for your platform... using builtin-java classes where applicable
> 07/12/15 01:29:02 INFO io.TestMapFile: Writing 1000000 rows to
> testMapFileRandomAccess
> 07/12/15 01:32:04 INFO io.TestMapFile: Writing 1000000 records took 182009ms
> 07/12/15 01:32:04 INFO io.TestMapFile: Reading 1000000 random rows
> 07/12/15 01:48:02 INFO io.TestMapFile: Reading 1000000 random records took
> 958243ms
> Time: 1,140.652
> OK (1 test)
> {code}
> For the below test using TRUNK r604352, I amended the test so it output a log
> message every 100k reads:
> {code}
> [EMAIL PROTECTED] hadoop-trunk]$ ./bin/hadoop org.apache.hadoop.io.TestMapFile
> .07/12/15 01:56:34 WARN util.NativeCodeLoader: Unable to load native-hadoop
> library for your platform... using builtin-java classes where applicable
> 07/12/15 01:56:34 INFO io.TestMapFile: Writing 1000000 rows to
> testMapFileRandomAccess
> 07/12/15 01:59:38 INFO io.TestMapFile: Writing 1000000 records took 183986ms
> 07/12/15 01:59:38 INFO io.TestMapFile: Reading 1000000 random rows
> .........
> {code}
> After 20 minutes it still hadn't printed out the 'read 100k messages' (I had
> to leave -- will fill in final figures later)
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